Squamous cell carcinoma (SCC) is the most common form of cervical cancer. The mortality rate for SCC has decreased dramatically over the past 30 years because of the success of cervical cytology in detecting potential precursor lesions, designated atypical squamous cells of undetermined significance (ASCUS) low grade squamous intraepithelial lesions (LSIL) and high grade squamous intraepithelial lesions (HSIL). Despite this success, however, cervical cytology has come under increasing attack in recent years due to problems of false negative diagnoses. The rate of false negative results will be decreased if sensitive molecular assays are developed to detect cytologically abnormal cells. Human papillomavirus (HPV) is the best known molecular marker of malignant and premalignant lesions of the cervix. Sensitive assay systems have detected HPV DNA in a high proportion of cases of LSIL, as well as in most cases of HSIL. HPV detection in cervical cytology specimens has been limited, however, by a low level of specificity for clinically significant cervical lesions, due in part to the high prevalence of HPV DNA in cervical smears from cytologically normal women. Telomerase expression, a marker of cellular immortalization, can be detected by the telomeric repeat amplification protocol (TRAP) in most malignant tissues but is present at low or undetectable levels in most normal somatic tissues. Preliminary studies from my laboratory have shown that the TRAP assay has a sensitivity of 65 percent and a specificity of 96 percent for the detection of LSIL/HSIL/SCC versus normal/benign reactive or ASCUS cytology of patients undergoing colposcopic examination. Furthermore, telomerase analysis detected 75 percent of cases of HSIL and 100 percent of SCCs. These initial studies, however, are limited by the small number of cases that have been evaluated to date. The goal of this proposal is to determine the potential of telomerase analysis to decrease false negative rates in cervical cytology, by investigation of the following specific aims: 1) correlate telomerase expression and the detection of HPV DNA with cytologic diagnosis of cervical smears collected at the time of colposcopic examination, as a marker of ASCUS, LSIL, HSIL and SCC; 2) correlate telomerase expression and detection of HPV DNA in cervical cytology preparations, from patients undergoing colposcopic evaluation, with a current cytologic diagnosis of normal/benign reactive changes, ASCUS, or LSIL with the concurrent or subsequent detection of HSIL or SCC; and 3) compare the cellular localization of telomerase with the localization of HPV DNA in normal/benign reactive cervical tissues, LSIL, HSIL and SCC.